Always learn and follow the acceptable use policy.
Don't tie up computers in public labs with game playing when other people need to work and are waiting for a terminal.
Always end your messages with your name and e-mail address.
Always include a subject heading with e-mail.
Only forward a message if it is appropriate and if doing so will not harm the reputation of the writer. If in doubt, get permission to forward the message from the original sender.
In e-mail, use judicious quoting.
Take reasonable card with your punctuation and spelling, and don't write in all capitals SINCE IT LOOKS AS IF YOU ARE SHOUTING.
If you quote e-mail in another venue - a paper, article, online essay, etc. - try to get permission from the writer you are quoting.
Always give proper credit for anything you use of find on the Internet.
Make sure you write down all the information needed for others to go to the source you have cited.
Never use shareware (software available to the public at low prices and paid for on the honor system) without paying the fee for it.
If you get flamed, do not flame in return. Stay cool and respond with wit and good humor. It will make you look cool and make the flamer look bad.
Taken from Writing Online: A Student's Guide to the Internet and the World Wide Web. Crump & Carbone. 2nd edition. Houghton Mifflin. New York. 1998.